The role of plasma instabilities in relativistic radiation-mediated shocks: stability analysis and particle-in-cell simulations
Jan 14, 202212 pages
Published in:
- Mon.Not.Roy.Astron.Soc. 511 (2022) 2, 3034-3045
- Published: Feb 24, 2022
e-Print:
- 2201.05494 [astro-ph.HE]
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Abstract: (Oxford University Press)
Relativistic radiation-mediated shocks are likely formed in prodigious cosmic explosions. The structure and emission of such shocks are regulated by copious production of electron–positron pairs inside the shock-transition layer. It has been pointed out recently that substantial abundance of positrons inside the shock leads to a velocity separation of the different plasma constituents, which is expected to induce a rapid growth of plasma instabilities. In this paper, we study the hierarchy of plasma microinstabilities growing in an electron-ion plasma loaded with pairs and subject to a radiation force. Linear stability analysis indicates that such a system is unstable to the growth of various plasma modes which ultimately become dominated by a current filamentation instability driven by the relative drift between the ions and the pairs. These results are validated by particle-in-cell simulations that further probe the non-linear regime of the instabilities, and the pair-ion coupling in the microturbulent electromagnetic field. Based on this analysis, we derive a reduced-transport equation for the particles via pitch-angle scattering in the microturbulence and demonstrate that it can couple the different species and lead to non-adiabatic compression via a Joule-like heating. The heating of the pairs and, conceivably, the formation of non-thermal distributions, arising from the microturbulence, can affect the observed shock-breakout signal in ways unaccounted for by current single-fluid models.Note:
- 12 pages, 9 figures
- instabilities
- plasmas
- radiation mechanisms: general
- shock waves
- methods: analytical
- methods: numerical
References(40)
Figures(19)